A variety of volatile substances such as fragrances, essential oils, pesticides are contained in many and various forms of containers to control the release of vapor from the volatile substances for the purpose of air freshening, deodorizing, aromatherapy, air purification, air cleaning, pest repelling or pest killing. The volatile substances generally exist in the liquid or solid form.
One example of the containers in the art is of sachet type, which is made from a non-woven material (FIGS. 1 and 2). The sachet type container is not liquid proof, thus the volatile substances contained therein is limited to dry solids, otherwise the seepage or staining of the sachet material by a liquid content may occur. Usually, a porous filler material, such as sponge, foam, cork or wood, is arranged in the container to absorb the volatile substances. Since the volatile substances have to remain dry as mentioned above, the concentration of the volatile substances in the filler material is kept at low level. In some cases, the volatile substances are incorporated into a polymeric resin and injection or extrusion molded as beads, the concentration of the volatile substances are increased but remain as low as less than 50%. As a result of the low concentration of volatile substances, the treatment intensity of this type of product is very low, which means that the space to be treated is limited.
A further example of the container for the volatile substances is the type which has a vapor impermeable and rigid container 1 for the volatile substances 5 with an opening, and a membrane closure 2 firmly affixed to the opening of the container (FIGS. 3 and 4). The membrane closure 2 is provided as a single multilayer structure comprising a top layer 3 which is vapor impermeable and a bottom layer 4 which is vapor permeable. The interface between the vapor impermeable top layer and the vapor permeable bottom layer is intentionally produced with a low binding force to allow easy removal of the top layer from the bottom layer, so that the volatile substances can begin to escape when the product is to be used. The membrane type container is made from a stiff, impermeable material which can be molded into shape to form a containment area for the volatile substances and then is heat sealed to the membrane closure. The disadvantage of this container is that it is limited to shapes and designs which are flat and stiff, since the multilayer structure of the membrane enclosure cannot withstand curvature or flexing during storage as delamination of the interface between the top layer and the bottom layer may occur, leading to a premature vaporization of the volatile substances, hence shortening of the shelf life of the product. Another drawback is that the vapors can be dispensed from one side of the membrane enclosure only. The third drawback is that the membrane type product is stiff and hence cannot be inserted into narrow spaces like air vents.
The sachet type and membrane type devices are meant for use in small spaces such as cars, wardrobes and rooms. In order for imparting an air treatment effect to bigger commercial spaces such as retail stores, hotel lobbies, office buildings or shopping malls, there are machines commercially available which nebulize volatile substances into a particulate form and spray them into the air or air ducts. However, this approach requires mechanical installation, electricity and maintenance, which increases the costs of implementation.
Therefore, there is a need for a new device for delivering volatile substances which can solve the previously described drawbacks of the prior art and cater for all occasions in a simple and economic manner. Thus, the invention entails the task of creating a simple and cost-effective device that exhibits excellent storage stability and barrier properties and also provides the flexibility in all occasions including the commercial applications.